syzbot

 </TASK>
kobject: kobject_add_internal failed for hci5:201 with -EEXIST, don't try to register things with the same name in the same directory.
Bluetooth: hci5: failed to register connection device
==================================================================
BUG: KASAN: slab-use-after-free in l2cap_sock_ready_cb+0xd6/0x170 net/bluetooth/l2cap_sock.c:1687
Read of size 8 at addr ffff88803109f200 by task kworker/u9:0/8472

CPU: 1 UID: 0 PID: 8472 Comm: kworker/u9:0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: hci5 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 l2cap_sock_ready_cb+0xd6/0x170 net/bluetooth/l2cap_sock.c:1687
 l2cap_chan_ready net/bluetooth/l2cap_core.c:1264 [inline]
 l2cap_le_start+0xb0d/0x13b0 net/bluetooth/l2cap_core.c:1376
 l2cap_conn_ready net/bluetooth/l2cap_core.c:1629 [inline]
 l2cap_connect_cfm+0x6aa/0x10e0 net/bluetooth/l2cap_core.c:7305
 hci_connect_cfm+0x95/0x140 include/net/bluetooth/hci_core.h:2131
 le_conn_complete_evt+0xf65/0x1420 net/bluetooth/hci_event.c:5821
 hci_le_conn_complete_evt+0x187/0x480 net/bluetooth/hci_event.c:5847
 hci_event_func net/bluetooth/hci_event.c:7716 [inline]
 hci_event_packet+0x78f/0x1260 net/bluetooth/hci_event.c:7773
 hci_rx_work+0x3ee/0x1060 net/bluetooth/hci_core.c:4076
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Allocated by task 11582:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5657 [inline]
 __kmalloc_noprof+0x23e/0x7e0 mm/slub.c:5669
 kmalloc_noprof include/linux/slab.h:961 [inline]
 sk_prot_alloc+0xe7/0x220 net/core/sock.c:2245
 sk_alloc+0x3a/0x390 net/core/sock.c:2301
 bt_sock_alloc+0x3b/0x310 net/bluetooth/af_bluetooth.c:151
 l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1897 [inline]
 l2cap_sock_create+0x147/0x330 net/bluetooth/l2cap_sock.c:1939
 bt_sock_create+0x163/0x240 net/bluetooth/af_bluetooth.c:135
 __sock_create+0x4b3/0x9d0 net/socket.c:1605
 sock_create net/socket.c:1663 [inline]
 __sys_socket_create net/socket.c:1700 [inline]
 __sys_socket+0xd7/0x1b0 net/socket.c:1747
 __do_sys_socket net/socket.c:1761 [inline]
 __se_sys_socket net/socket.c:1759 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1759
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 11582:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6670 [inline]
 kfree+0x1bd/0x900 mm/slub.c:6878
 sk_prot_free net/core/sock.c:2284 [inline]
 __sk_destruct+0x626/0x880 net/core/sock.c:2384
 l2cap_sock_release+0x1c1/0x270 net/bluetooth/l2cap_sock.c:1438
 __sock_release net/socket.c:662 [inline]
 sock_close+0xc3/0x240 net/socket.c:1455
 __fput+0x45b/0xa80 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0xef/0x4e0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88803109f000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 512 bytes inside of
 freed 2048-byte region [ffff88803109f000, ffff88803109f800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x31098
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813ff27000 ffffea0000f3ec00 dead000000000002
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813ff27000 ffffea0000f3ec00 dead000000000002
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 0080000000000003 ffffea0000c42601 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 44, tgid 44 (kworker/u8:3), ts 919572640031, free_ts 919329918532
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
 prep_new_page mm/page_alloc.c:1865 [inline]
 get_page_from_freelist+0x28c0/0x2960 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3b0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xb10/0x13e0 mm/slub.c:4656
 __slab_alloc+0xc6/0x1f0 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0x2bf/0x810 mm/slub.c:5764
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:608
 __alloc_skb+0x204/0x3a0 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 inet6_ifinfo_notify+0x70/0x120 net/ipv6/addrconf.c:6179
 addrconf_notify+0xca0/0x1050 net/ipv6/addrconf.c:3760
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 netif_state_change+0x26f/0x380 net/core/dev.c:1584
 linkwatch_do_dev+0x117/0x170 net/core/link_watch.c:186
 __linkwatch_run_queue+0x56d/0x7e0 net/core/link_watch.c:244
page last free pid 9911 tgid 9911 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0xfe1/0x1170 mm/page_alloc.c:2943
 __slab_free+0x2e6/0x330 mm/slub.c:6004
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_node_noprof+0x23c/0x6f0 mm/slub.c:5315
 __alloc_skb+0x1dc/0x3a0 net/core/skbuff.c:679
 netlink_sendmsg+0x5c6/0xb30 net/netlink/af_netlink.c:1869
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 __sys_sendto+0x3c7/0x520 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803109f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88803109f180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88803109f200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88803109f280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88803109f300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================